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re: wire selection / basic construction questions

Original poster: Terry Fritz <teslalist@xxxxxxxxxxxxxxxxxxxxxxx>

Hi Ian,

At 06:56 AM 6/29/2005, you wrote: 
I'm not quite sure how this tesla list works, but I'm gonna give it a
shot.


I think you have it figured out ;-)

Im fairly new to the world of high voltage electronics, but do
have some experience.  I've built tesla coils before, but never
investigated their working to the extent present on the tesla list.
Also, some of the discharge lengths that are claimed on the list are
very impressive; the longest I have achieved is close to 6" so far.
Anyways, I'm going to try and build a properly tuned coil as described
on the many emails that I have followed for some time.  I have most of
the components that I'm going to use and just had a few questions
before I actually build anything.

What I have currently available to me are several neon sign
transformers to choose from for the power supply, two matched Maxwell
0.47uF 35KV pulse capacitors, most of the hardware necessary, and
several gauges of magnet wire.

0.47uF is a very high value. If they were 0.047 you could put them in series to get about the capacitance you need. Here is a NST vs cap size chart:

http://hot-streamer.com/temp/MMCcapSales.gif


Here goes:
1) What is the best gauge of wire to use for the primary and
secondary, and any reasoning as to why --> ie: rules of thumb?

Most secondaries are about #24 gauge magnet wire. Primaries are usually 1/4 inch refrigeration copper tubing. It comes in a 50 foot roll from the hardware store for about $15.


2) A few posts back, there was a mention of the h/d ratio of the
secondary not to exceed 5:1.  Has anyone found an 'optimum' ratio,
considering optimum to be a loose term based on many other factors.

Not really... Just don't make it too short or the sparks will hit the primary all the time... I would proportion the coil so "it looks good". Don't make it real skinny


3) Is there a benefit to including an RF choke into the primary circuit? 

No.  The choke does nothing or might ring and hurt the transformer:

http://hot-streamer.com/TeslaCoils/MyPapers/rcfilter/rcfilter.html

http://hot-streamer.com/TeslaCoils/Misc/NSTFilt.jpg


4) I'm having trouble sourcing the tungsten for the spark gap setup,
does anyone have any suggestions here, or other materials that have
worked well for others that I can use?

Any welding shop should have 1/8 inch diameter x 7 inch long "TIG welding rod". Brass rod can be found at the hardware store. Steel is an option too but I like to avoid magnetic materials in RF circuits.


5) Besides using two stainless steel cooking bowls to form the
torroid, does anyone have any other ideas?

Corrugated aluminum dryer duct from the hardware store is commonly used. Many big hardware stores have other sizes too.

Cheers,

        Terry





Thanks for all your help.  I welcome any and all comments and
suggestions and cant wait to start building.


--
Ian "Foci" Swentek

TTFN